1. Field of the Invention
The present invention relates generally to denture adhesive compositions, and particularly to the vehicles or mobile phases thereof.
2. Description of the Prior Art
A variety of denture adhesives are known and commercially available in the form of creams, pastes and the like. These adhesive compositions generally comprise a gum phase, constituted by one or more non-toxic polymeric compositions, that are selected and formulated to provide the desirable adhesive properties between the denture and the adjacent structure in the user's mouth. The adhesive or gum phase usually comprises about 30 to 75% of the total adhesive composition, and a vehicle or mobile phase is included, comprising the remainder, for the purpose of providing flowability, smoothness of texture, and the other properties desirable to make the adhesive composition pleasant to utilize as well as effective. The mobile phase frequently consists of a mineral oil base that may be utilized alone, or together with other modifying ingredients such as flavors, colorants, extenders and other adjuvant materials. A particular mobile phase composition includes a mineral oil and a polyethylene wax possessing a molecular weight ranging from about 1500 to about 2500. This composition is disclosed in U.S. Pat. No. 3,215,599, to Thau,etal. Denture adhesives are generally disclosed in U.S. Pat. No. 3,833,518, to Rubin et al., and U.S. Pat. No. 3,003,988, to Germann et al., both disclosures of which are incorporated herein by reference.
With respect to the vehicle or mobile phase disclosed in Thau,etal., denture adhesive creams prepared with even this base or mobile phase, exhibit difficulty in extrudability, when the creams are packaged in tubes for commercial sale. In particular, excessive force is required to expel the cream from the tube, with the frequent result that either the tube will rupture over time, or the excessive force anticipated to expel the cream will result in the expulsion of more cream than is necessary for a particular application. In either event, the difficulty with extrudability of the denture adhesive creams has been a problem frequently reported by denture wearers.
Efforts have been made in the past to improve the extrudability of mobile phases or gels employed in ointments, and the like, without adversely affecting their consistency or texture. Such investigations were reported in Eros et al., "Investigation of the Rheological Characteristic of Ointment Gels Containing Emulsifiers and Emulsion-Type Ointments", Cosmetics & Toiletries, Volume 94, Pages 67-79, Allured Publishing Corp., New York, (1979). The authors incorporated emulsifiers including sorbitan monostearate into the gels at various concentrations, and examined the viscosity and spreadability of the resulting preparations. Sorbitan monostearate was found to exhibit improved spreadability, related to lowered viscosity, in amounts of from about 2.5% to 5.0% by weight. Outside of this range, the improved properties either were diminished or did not exist. In either event, a correlation between the presence of sorbitan monostearate and improvements in gel extrudability was not drawn, and was not apparent from the data gathered by the authors.
A need therefore exists for the development of a denture cream, and particularly, a mobile vehicle therefor, that offers improved extrudability, while retaining the desirable properties of gel-like viscosity and smooth coherent texture, necessary and desirable in denture adhesive preparations.